Integrated circuits (ICs) are generally fabricated in an array on or in a semiconductor substrate. ICs generally include one or more layers formed over or in the substrate. The one or more overlying layers may be removed along scribing lanes or streets using a mechanical saw or a laser. After scribing, the substrate may be throughcut, sometimes called diced, using a saw or laser to separate the circuit components from one another.
When laser processing is used, the results tend to be highly material dependent. For example, a first laser type (or set of laser parameters) may be ideal for cutting semiconductors, while a second laser type (or set of laser parameters) may be ideal for cutting metals.
One example of a challenging problem is the singulation of semiconductor devices mounted on die attach film (DAF), a process sometimes referred to herein as “DAF dicing.” This problem may be addressed in production by using mechanical diamond saws with ultra-thin blades because laser dicing with known processes tend to produce a die with lower mechanical strength compared to that produced by mechanical sawing. Incorporation of fragile low-k dielectric materials into these semiconductor devices along with reduction of the silicon wafer thickness has increased the difficulty for mechanical saw dicing, leading to slower throughputs and more yield losses. Using a traditional laser-only process for DAF dicing of thin silicon wafers also typically results in increased die pick failure (reduced die yield) manifested as, for example, uncut DAF (“double die”), overcut DAF (“anchoring”), and/or low die break strength (due to etch variance when etching after laser dicing the DAF).
Previously attempted solutions for DAF dicing include using lasers to scribe the low-k dielectric and/or semiconductor layers prior to mechanical saw dicing, combining laser dicing with a post-dicing etch process to strengthen the die, using a full-cut laser dicing system with two different lasers (or different sets of laser parameters such as pulse width), or freezing the DAF and stretching it until the tape fractures. A known method for dicing through both the semiconductor device and the DAF using a single laser dicing strategy results in a deposition of DAF material on the sidewalls of the semiconductor dies such that a subsequent xenon difluoride (XeF2) etch process is adversely affected by this “DAF splash.”